Switching or telephone system.



PATENTED SEPT. 25, 1906.

A. E. KEITH. SWITCHING OR TELEPHONE SYSTEM.

APPLICATION FILED MAR.9,1905.

6 SHEETSSHEET 1 ljflwwzw fag $65 No. 831.876. PATENTED SEPT. 25, 1906 A. E. KEITH.

SWITCHING 0R TELEPHONE SYSTEM.

APELIGATION FILED MAR.9,1905.

a SHEETS-SHEET 2 No. 831,876. PATENTE'D SEPT. 25, 1906. A. E. KEITH.

SWITCHING OR TELEPHONE SYSTEM.

APPLICATION FILED MAR.9,1905.

SHEETS-SHEET 3 W??? Ma fiz cw M L 0J g jizwweyg,

NO. 831,876. PATENTED SEPT. 25, 1906 A. E. KEITH. V SWITCHING OR TELEPHONE SYSTEM. 7

APPLICATION FILED MAB..9,1905.

6 SHEETS-SHEET 4 w a I g QQ V \mm/ x \f g 1 No. 831,876. I PATENTED SEPT. 25, 1906. A. E. KEITH.

SWITCHING 0R TELEPHONE SYSTEM.

APPLICATION FILED MAR. 9, 1905.

8 SHEETS-SHEET'i No. 831,876. PATENTED SEPT. 25, 1906 A. B: KEITH.

SWITCHING 0R TELEPHONE SYSTEM.

APPLICATION FILED MAR. 9, 1005.

6 SHEETSSHBR1G.

zTED STATES PATENT ion. 1

ALEXANDER E, KEITH, OF CHICAGO, ILLINOIS, ASSIGNOR TO AUTOMATIC ELEC'IRIC COMPANY, OF CHICAGO, ILLINOIS.

SWITCHING CR TELEPHONE SYSTEM- izo. 881,876.

Specification of Letters Patent.

Patented Sept. 25, 1906.

Application filed March 9,1905- Serial No. 249,189-

To all whom, it may concern.-

Be it known that I, ALEXANDER E. KEITH, a citizen of the United States of America, and

*a resident ofChicago, Cook county, Illinois,

have invented a certain new and useful Improvement in Switching or Telephone Systems, of which the following is a specification.

am aware, to locate first selectors, sec

ond selectors, and connectors, as they are commonly called, on boards or frames by themselves, thus making complicated and renderi "it quite cult to-trace or locate calls, ith my improved arrangement, however, which provides for, say, one hundred first selectors with the necessary second selectors and connectors for [trunking on the same board, the Wiring is very much simplified, and,furthermore, calls are much more easily traced or located by the attendant at the exchangethat is to say, if an attendant sees a second selector, for example, off normal, so to speak, he is with my lmproved arrangement able to tell at once exactly from which board of first selectors the call came, and this is of course also true of the connectors. v

Still another and one of the principal ad vantages of my improved arrangement consists in this that the original installation of any exchange may be of any desired size and that additions maybe made at any time without interfering with the apparatus which is in use at the time it is desired to enlarge or extend the capacity of the exchange. Again, my improved method (1? Wiring insures an advantageous and economical distribution of the work or load, as it is sometimes called, among the different second selectors and connectors, which is a great advantage and material improvement, inasmuch as by so doing the Wear on these switches is rendered uniform; also, as will hereinafter more fully appear, my improved method of wiring is a plicable to telephone systems including both automatic and manual switchboards or to systems including only manual switchboards that is to say, exchanges in which the connections are made by operators rather than by automatic switches.

More specifically considered and to the foregoin and other useful ends, my invention contemp ates as one feature of improvement a system comprising a plurality of switchingpositions-such, for example, as a plurality of automatic switches or a plurality of telephone-operators switching positions and a plurality of trunk-lines leading to said positionstogether with terminalssuch, for example, as the contacts of automatic switches or the contacts of the spring-jacks usually employed in manual-board systems, these terminals being connected with the other ends of said trunk-lines orother line-conductors, the said terminals being arran ed in a plurality of groups, and in each case a l terminals connected with a particular trunk-- nals occupying similar or like ositions in the different grou s are connecte respectively, with as many 'flerent trunk-lines and whereby the telephone-operator, automatic switch, or whatever other provision may be made for each groupoffsubscribers will have first chance, so to speak, at aterrninal connected with a trunk-line other than those .atwhich any other operator or switch allotted to other groups would have first chancein endeavoring to select an automatic trunkline -that is to say, if the operator or switchallotted to one group of terminals makes connection With the first terminal in such group the operator or switch allotted to another group may then select another or non-busy trunkline by making connection with the first terminal, it being possible in this way for all of the operators to plug into the first jacks or terminals of their respective groups of terminals or for all of the automatic switches to make connection with the first terminals in their respect'ivegroups and still all attain connection with as many difierent trunklines, the possibility or probability of each operator or switch when called upon to select an idle trunk-line being able to make such a selection by simply selecting the first terminal in the roup and without going any farther being argely and quite advantageously increased.

' To these and other ends, however, my invention consists in matters hereinafter set forth and claimed.

In the accompanying drawings, Figure 1 is a diagrammatic floor-plan, so to speak, of an automatic telephone-exchange, embody ing the principles of my invention. Fig. 2 is a erspective of a portion of said automatic teiiephone-exchange or of an exchange of smaller capacity. Fig. 3 is a diagram illustrating the-method of multi lying together the contacts of the same or iikebank-levels in the different automatic switches of a single frame or switchboard. Fig. 4 is a diagram illustrating the; method of multiplying to ether the contacts of like or similar bank evels of the automatic switches of a plurality of groups of switches -that is to say, of a plurality of frames or switchboards. Fig; 5 is a simplified diagram illustrating what is shown in Fig. i that is tosay, showing ten distinct groups of terminals, but all of the same level, as it is called, and connected with the second selectors or with the connectors, as the case may be. Fig. 6 is a diagram similar to Fi 5, but showing my invention applied to t e trunking between an auto matic exchange and a manual exchange. Fig. 7 is a diagram illustrating the applica tion of my invention to the trunking between two manual board telephone exchanges. Fig. 8 shows an ordinary spring-jack and operators switch-plug for making connection with a trunk-line, as hereinafter described. 9 shows the bank-contacts, shaft, and shaft-wipers of a well-known form of auto matic switch, such as; any of those hereinafter referred to, it being understood that any suitable mechanism can be employed for operating the said shaft in a well-known manner,

As thus illustrated and referring to Fig.- 1, it will be seen that thearrangement involves a completeten-thousand-subscriber system that 1s to say, an automatic exchange in which provision is made for service between substantially or ap roximatel ten thousand subscribers. It wi 1 be seen t at the switchframes, or switchboards, as they may be called, are in this diagram arranged'in rows of ten from bottom to top of the figure and also in rows of ten from left to right. As indicated in Fig. 1, each of the rows extending from. bottom to top represents a certain thousand in the exchange-that is to sa the first row to the left represents all su scribers numbers beginning with 1,000,

the second row all numbers beginning with 2,000, and so on to the last row, which represents all numbers in what is called the naught thousand. The naught in these numbers has a certain si nificance, for wherever it occurs it refers to t 16 tenth-thousand ou the tenth-hundred group, the tenth an -level, or the tenth contact in a level. On the other hand, and taki the rows which run from left to right (if the dia am, the bottom row represents all subscri ers numbers, the last three digits of sensve which amount to less than one hundred, while the next row represents all subscribers numbers the last three digits of which amount to one hundred and less than two hundred, and so. onto the to row, which represents-all subscribers num ers, the last three digits of which amount to nine hundred or over. For example, the first board at the lower left hand corner would be number 1,000 that is to say, it would have upon it all of the first selectors of subscribers whose numbers range from 1,000 to 1,099..

Again, the second board in this row would represent all the subscribers whose numbers range from ;1,100' to 1,199, and so on throughout this entire row to the board in the upper left-hand corner, which latter would have upon it the first selectors of all subselectors in callin into the thousand row or 'roup in which the board is located. As will iereinafter more fully appear, each board also carries the connectors, which are used by the entire exchangethat is, by any subscriber in the exchange-for calling any subscriber whose line terminates at this particular board. Referring again to thediagram,

it will be seen that the row running from left to right at the'bottom of the figure contains all boards representing subscribers numbers ranging from 1,000 to 1,099, from 2,000 to 2,099, from 3,000 to 3,099, &c., to the end'of the row, the second digit of any subscribers number in this row bemg invariably a naught or a zero or, in the case of the board in the lower right-hand corner of'this figure, all numbers from 1 r to 99, for it will be understood that in an ber, therefore, being 9,999. It is evident, therefore, that each of these rows leading from left to right and extending horizontally when the diagram is viewed in its proper position contains the firs selectors representing the same hundred-that is to say, all'of thefirst selectors in each of these rows represent SllbSCIlbGIS whose numbers have the same hundred, but whose numbers are found in different vertical or thousand rows. Fur- IIO exchange of this size no subscribers number has more than four digits, the highest num-' thermore and in a general way, the method of running the cables between these different boards is also shown inthis diagram. For example, the cable 1 extends from the firstselector banks to the second selectorswitches, these two kinds of switches being,- on the same board. Also, as shown, the cable 2, which is multiplied from this cable 1, .1 0

extends the connections of these selectorbanks to the different boards in this same hundred row-that is, it multiplies together all first selector-bank contacts in this particular row of hundreds. The cable 3 extends from the second-selector banks to the connector-switches, all of these'switches being on the same board, and also multiplies the second-selector banks on this particular board with the second-selector banks in every other board in this particular group of thousands, or thousand-row, as it may be called. In addition it will be seen from this diagram that the first-selector banks are multiphed together from left ,to right, so that the one-thousand board is multiplied with the two-thousand board, and then to the threethousand board, and so on to the right-hand end of the row. On the other hand, however, the second-selector banks are multiplied together from bottom to top of Fig. 1that is, from the one-thousand board to the eleven-hundred board, thence to the twelvehundred board, &c., the same in each vertical row, as will hereinafter more fully ap'pearn Looking at the diagram, the cable 4 extends from the connector-banks to the normal jacks, as they are calledth at is to say, to the devices by which the connector-line bank-terminals are connected through the selector-switch with their respect ve subscribers lines. -As illustrated, each of these cables is complete u on the board by which it is carried and to w 'ch it is allotted, and in this way the one hundred sets of bank con tacts or terminals, as they may be called, of the connectors are connected to the one hundred sets of normal jacks or subscribersline terminals of the first selectors on this particular board, there being, of course, but one set of normal jacks or terminals to each first selector. While the diagram shows a ten-thousand-subscribers s stem, it is evident that the s stematic, a vantageous, and scientific distribution and relative arrangement of the difierent switches, boards, and of the cabling can be applied to an exchange of any desired sizeor capacity.

Referring more particularly to Fig. I 2,

which shows only twelve boards and which might serve as a tWelve-hundred-line ex-' change, but having an ultimate ca acity of approximately ten thousand subscri ers, this figure illustrates the relative location of the first selectors, second selectors, and connectors, the first selectors X being shown on the four lower shelves of each'board, the second selectors Y being shown at the left-hand end of the uppermost shelf of each board, and the connectors Z being shown at the ri ht-handend of the u ermost shelf of eac board. As shown in t 15 perspective view, the cabling from the first-selector banksis illustrated as extending, b way of cable 5, forexample, to the terms. board 6, this particular cable being known as the bank-cable, thence from the terminal board 6. The first level of the first-selector banks on the board A is ,trunked to the second selectors Y on said board by means of the cable 11, which latter is commonly known as the first-selector trunk-cable. Also, as will be seen, the ca-- ble 7, commonl known as the first-selector multi lying ca le,multiplies the contacts of said fili-st level to the terminal board 8 and to the second selectors of the board B, also to the terminal board 9, and so on throughout this articular hundred-row and from each of said boards 8 9, &c., to the first-selector-bank contacts of thefirst level of the boards B C, &c. The same arrangement follows with respect to the second level of the first-selector bank-contacts of the board B, in

which case the bank-cable leads to the terminal board 8 and from thence, b means of made with the second selectors of the board B. Multiple connections are also made from, the terminal board 8 and by way of the selector multiple cable 7 in both directions with the terminal boards 6 9, &c., and from the said terminal boards to the bank-contacts of the second level of the first selectors of the boards A C, &c. A similar arrangement is followed with respect to the third board C, in which case the third level is connected to the terminal board 9, from whence multiple connections are made to the second selectors of the board C. by way of the selector multiple cable 7 to the terminal boards 6 8, &c., and with the bank-contacts of the'third level of .the first selectors of the third level in the said boards, and so on throughout. the exchange. It is therefore evident that the second selectors of the first board A are allotted to the first level of the front row of boards A B, &c. The second selectors of the board B are al-- lotted to the second level of the same boards, and the second selectorsof the board C are allotted to the third level of the same boards, and so on. A similar arrangement follows with respect to the second or one-hundred row of boards in line with the boards D and likewise with respect to the third or second hundred row of boards, including the board G, and so on. At each one of these. boardsas, for example, the board Aa first-selector trunk-cable 11 is installed, one end of which is suitably connected to second selectors on this board, the other end of which is connected at the terminal board 6 to contacts which are wired to bank-contacts of one level of the line-banks and the corresponding level of the private banks of all first selectors in this oard. In this way the arrangement is such that if a first selector on the board A, for example, has its wi ers in engagement with the first bank-leve s of thehne and private banks, respectively, of the first selector-banks,

this connection will be extended 1 through to one of the second selectors Y of this board A; but if the same first selector has its wipers placed enga ement with the second bankevels (line an private) of the board A, connection will then be extended through to the second selectors Y of the board B, and in a tor-shaft wipers wit similar way the engagement of the first-selec- 1 the third bank-levels (lime and private) would result in extending the connection throu h to the second selectors of the board C. In ot ier words, the first selector of any board when operated by its allotted subscriber, or in any other wa icks out a second selector inthe desire t ousandrow. In the same manner if a first selector on the board B called in on the first banklevels (line and private) of the first selectors it would be immediatel connected witha second-selector on boar A; but if this same first selector called in on the third bank-levels of the first selectors the connection would then be extended to the second selectors on board thirt -two-hundred'board,) depending u onv 0. Again, the board D would be wired in such manner that the calling in on different banklevels of first selectors of this board would result in extending the connection to the second selectors on the board D, (the twelvehundred board,) to board 'E, (the twentytwo-hundred board,) or to board F, (the whereas if the call were made in the second bank-levels of the second selectors of .this board the connection would then be extended through to a connector on the board D,

assuming this latter board to be the twelve-- hundred board, or, if any particular second selector called in on the third levels the connection would then extend through to a connector on board G, which latter may be considered as the thirteen-hundred board. The cable 12, which extends from the second-selector bank-terminal (not shown) to the connector-jacks on the same board with the banks, is commonly known as a second-se lector trunk-cable. The cable 13, which multiplies together the second-selector bankterminals on the different boards, is commonly known as a second-selector multiple cable. Also the cable 10 is ordinarily known as the normal cable and extends from the connector-banks to the first-selector normal jacks, and the normal cable is always complete on its particular board and does not extend to other boards. As illustrated in board A, the one-hundred sets of contacts or terminals, representing all subscribers whose numbers range from- 1,100 to.

1,199 of the connector-banks, are connected with the one hundred first selectors on this board, and consequently with the onehundred subscribers-line terminals allotted to this board and each first selector, and therefore each subscribers line'terminating at this board, being connected with a difierent I set of connector-contacts.

In Fig. 3, which is a diagram showing the method of connectin together the contacts of any particular ban .-level'i n the first selectors of the board A, for example, the ten sets of contacts with which each switch isproQ- vided, or ten terminals, as they may be called, are shown. arranged in subdivisions, one subdivision for each switch and each subdivision consisting of a series of terminals arranged along a definite line, preferably a curved line, as shown. In this way Fig. 3 may be said to represent the first-levelterminals or contacts of all of the first-selector. switches and the manner in which they are multiplied together of aboard containin but forty first selectors, it being understoo however, that this 'arran ement would be carried out exactly as s own in aboard equipped with one hundred 'switches suc h, for example, as the board A. 21) In Fig. 3, however, it will be seen that all first-level terminals or contacts of the first selectors of the lower shelf are multiplied with the similar terminals or, contacts of the next higher shelf, and so on, to the top firstselector shelf, and it will also be observed that in each case all terminals or contacts occupying similar or like positions in the different switches of this particular board are multiplied together-that is to say, contact 1 in the first level of one switch is multiplied with the first terminals of. the first level of all other first selectors in this board, and this is true of all of the other contacts or terminals. In a smilar way all second contactsof' any given level are multipiled to ether. A 1 third contacts of any given leve -l are multi- (Shown in Fig.

roc

plied together, and this principle or method of wiring is preferably retained throu hout all of the first selectors of any parteular board. The cable 5 from the terminals .or-

contacts shown in Fig. 3, and which is knbwn as the bank-cable, leads to the terminal board 6. containing only the-conductors or wires of: this one bank-level, whereas in actual practice, as shown in Fig. 2, this cable Scontains In Fig. 3 this cable 5 is shown as the wires or conductors leading "from. all of the first-selector bank levels on this particu-. lar board. For convenience of illustration the wiring in Fi 3 has been shown as conf' sisting merely o? a single wire leadingfrom each terminal or set of contacts; but it will be understood that in practice each terminal thus shown diagrammatically consists, preferably, of three contacts," one for each side of y the line eircuit-and one-for the private-bank, 1 o

and that three wires or conductors lead from contacts or terminals of one board with the corresponding level of every other board in the particular hundred-row to which the same belong. For example, 17 may represent the terminals inthefirst or lowermost level of any first selector in the board A, it being remembered that the similar terminals or contacts of all other first selectors in this board are multiplied together and connected with these corresponding contacts or termiswitch in the board B,'the

nals of this particular switch, as shown in Fig. 3, and in the same way 18 may represent the first-level bank-contacts of afirst-selector I reviously-described method of connecting h e contacts or terminals being also true of this board, and 19 mayrepresent the first levelof a first selector in the board C, and so on to the first level in the board at the end of this particular hundred-row. It must be borne mind, however, that this method of wirin .ap lies either to the line or private bankeve s of either first selectors or second selectors or even to third selectors if the arrangement is to be a plied to a system having a capacity of one hundred thousand. subscribers that is to say, a system in which the subscribers numbers run as high as five digits. If these are to be considered as bank-levels of first selectors, then 17 may represent any banklevelsay the fifth, line, and private, respectively-of all the first selector on board A in Fig. 2, and 18 would represent the same bank-level of first selectors on the board B, and 19 would represent the same bank-level on board C, and so on to the end of the row. In this diagram, Fig. 4, 20, 21 ,22, &c., represent the second selectors to which these firstselector bank-contacts are connected. The. method 'of wiring is as follows: The line and private bank-levels of the first selectors of the different boards are suitably connected to the line and release trunks of second "selectors and illustrate the distribution of the work or load in such manner that the first selectors on one board call 1n first upon a certain second selector, while u on another board the first selectors call in rst upon a different second selector, thereby advantageously and economically dividing the load or work among the ldifferent second selectors. The first selector on the board hav-- ing bank-level 17, the latter having its wipers connected with the first contact will be connected through to the second selector 20, whereas the first selector on the board having the bank-level 18 in order to call this same second selector 20 must have its wipers connected with the tenth set of bank-contacts or terminals, and the first selector on the board having bank-level 19, if calling in on the ninth set of bank-contacts or terminals, will be connected with this same second selector 20. Considered in another aspect, however, while the first selector on the board having bank-level 17 calls second selector 20 by engaging the firspset of 'acks, first selector on the board having ban -level 18 in calling in on its first set of contacts or terminals would be connected with the second selector 21, and similarl the first selector onthe board having ban level 19 would be connected with second selector 22,and thus it is true that the first selectors on each board have the first chance to call a given second selector, while the first selectors on the difierent boards each have the first chance at calling a different switch. It will be understood, of course, that this method of wiring applies to all of the bank-levels between boards, whether firstselectors, second selectors, or, in'case of one hundred thousand systems, third selectorsthat is to say, if bank-levels 17, 18, and 19 are -cpnsidered as second-selector banklevels swit es 20, 21, and 22 would in such case be con ectors, and the same eneral arrangement f connection would e carried out in the anner already explained; The wires 7 are the multiple-cable wires, either first-selector multiples or second-selector multiples, d pending u on whether they multiply tog ther first-se ector banks or second-selector banks.

In Fig. the method of wiring shown in Fig. 4 is shown in a simplified form. In. this arrangement 23, 24, and 25 represent second selectors20, 21, and-22 of Fig. 4, groviding this diagram is to be considere in connection with a call coming from first-selector banks. The rows marked 1000, 2000, 3000, 4000, &c., represent a 1givenbank-levelof first selectors on different cards, such as the levels shown in Fig. 4. The small circles 26, 27, 28, &c.,re resent bank-contacts on these. different oards. For example, 26 would be the first set of con-' tacts on this bank-level on one board, such as the first contact on the level of bank-level 17 Fi 4, 27 the second set of contacts or termina s of the same bank-level, and so on. The strai ht lines, as shown, represent the electricaI circuits or connections from these different bank contacts or terminals through .to the switches 23, 24, 25, &c. In this way it will be seen by tracing one circuit from contact 26 that in the one thousand group the first selectors calling the first contact or terminal 26 are thereby connected with the 0 IIO switch 23, first selectors in the two thousand 'group calling the tenth contact .or terminal 29 are connected with switch 23, in the three thousand group calling the ninth contact or terminal, and in the four thousand group the eighth contacts are connected with switch 23, and so on. In this same one thousand 2o connection with second-selector banks the .rows which are marked 1000, 2000, -3000, 8cm, would then be marked 1100f, 1200 1300, &c. Furthermore, the second-selector banksand the connector-banks of each separate board are connected together, as shown in Fi 3that is, the contacts' are directly m tiplied together, the first contacts of one bank-level being all connected together at different switchesx Obviousl should an attendant be standing in front of arltll-yparticular board in the exchange and see o y the second selector'No. '1 in operation he would know the call .came from a first selec- 3 5 tor-on a board in the same hundred and in the onethousand groups, In like manner if he sees only the'second selector No. 2 in operation he knows that the call comes from a first selector in the same hundred, but in the 0 second thousand, or if the third second selector is in operation he knows that the call comes from the'same hundred, but from the third thousand. Again, should he see.only connector No. 1 in operation he would know that the call came from a second selector on the first or naught (0) hundred board of that particular thousand group, and if he should observe a second connctor'in operation he would know instantly that this particular call came from the same thousand group, but 'from the second or first hundred board. Ob-

viously 'this cross connecting of terminal contacts, as shown in Figs. 4 and 5 and for the purpose of distributing the load or work,

- .5 5 is accomplished entirely by the multiple cables between difierent boards. 7 In Fig. 6 an arrangement is'shown embodying my'invention for trunking from an automatic exchange to switchboard-operao .tors positions in a manual exchange. In

diagram the circles represent trunking o eratorsjpositions, the work Of'Whfch; opera 01's is, it will be readily understood, tom- 1 ceive and handle incoming calls from the au- 5 tomatic exchange. Ten operators positions business to be hand ed etween the two exthis method of wirin is such that '10, 11 to 20, '21 to 30,? &c indi at the terminals of a selectorbank-level used in calling the manual exchange. This terminal could of course be the end of a straight inultiple of onehundred switches, or one thousand switches or any other number of switches, dependin u on the amount of changes. In a general way the arrangement will be such that each of these rows would constitute a terminal of a group of switches of a proximately the same sizesay, two

hun red subscribers. The method of trunk ing from these difi'erent groups to the subscribers positions, so as to advantageously and economically divide" thework among.

the different operators, is illustrated by this dia am. *-As shown, the arrangement is suc that ,regardless of'which of the two hundred groupin the automatic exchange were the busiest, the work would be evenly divided among the operators, inasmuch as o erator No. 1, for example,.will be connecte to the first contacts or terminals in one group, the

tenth contacts or terminals in the next group numbered 11 to 20, the ninth contacts or terminals in the next group numbered .21 to 30/. and the eighth n the next, the seventh in the next, and so on. Obviously, there- 'fore, every other operator will be connected with the first contacts or terminals in one group, the second bank-contacts or terminals in another group, the third in another, and 100. so on, so that the subscribers of the automatic exchange will, in each group, have the first chance, so to speak, at a difierent operator, second chance at still a different operator, and so on. diagram does not, of I05 course, attem t to show the number .of trunksor trun -lines that would be actually employed between the automatic switch contacts or terminals and the o erators positions of the manual exchange. I t will be readily no understood, however, that should the automaticgroups be of the size sug ested there would then probably be ten trun s or trunk-, lines running into-each subscribers position,

one from each otthe bank contacts or terrni- 1 15 nalsthat is to say, the line illustrated as connecting each operators position with its allotted bank-contacts instead of being "a single conductor would consist of a cable -made up of one pair of conductors pickedup at each of the ten pairs of line bank-contacts orterminals w1th which suchoperatorsposiy 3 tion is connected.

In Fig. 7, which illustrates the 'applicability of m invention to trunking between two I25 manualoard telephone-exchanges the circles 1, 2, 3, 4, and 5 represent operators positions 1n one manual exchange, and circles 6, 7,' 8, '9, and 10 represent operators positions in another manual exchange. The black dots 11, 1 2, 13, 14, 15, &c., represent the trunkhne ack belonging to operators 6, 7, 8, 9, and 10, and the lines connectin the black dots to the circles 1, 2, 3, 4, and 5 re resent the trunks connecting the two exchanges and lllustrate a method of trunking that will, as previously explained, evenly divide the work of the operators both exchanges. For exam le, the trunk No. 11 of operator N0. 10 lea s to operator No. 5, No. 12 to No. 1, No. 13 to No.2,No.14 to No. 3, and No. 15 to No. 4, and with this arrangement the orders or calls of No. 10 are equally divided between the five operators at the otherexchange. Obviously, therefore, and in the same manner the orders or calls of No. 9 are equally divided between the operators in the other exchange,'or vice versa, if these trunks should be em loyed as two-way trunks and the black dots tiius made to represent drops and jacks of any suitable character for receiving incoming trunk-calls from exchangeA, as well as for carrying outgoing calls to exchange A, for in such case each operator at exchange A would have his articular trunk-lines or trunks equally divided between the operators of exchange B, as shown in the diagram.

As previously stated and for the broader purposes of my invention, a switching position may consist, therefore, of either an automatic switch or of one or more spring-jacks, &c., to be controlled andv operated by a single switchboard operator. If the switching positions are manually operated and controlled, then the spring-jacks and switchplulgs therefor may be of the character shown in ig. 8that is to say, of any suitable known oreapproved character. As shown, the sprin -jack H is ada ted to receive the plug w 10b is attache to the end of the ordinary flexible connecting-cord. If each switching position is represented by an automatic switch of any well-known character, then the bank-contacts and the shaft-wi ers thereof may be of the character shown in 9, it being understood that any suitable or well-known mechanism can be employed for operating the said shaft and its wipers. As shown, each automatic switch has a pair of line-wi e'rs J and a private wiper K, together with a ank of line-contacts L and a bank of private contacts M. For example, each first selector of the apparatus hereinbefore described ma be of the general character described an illustrated in Patent No. 815,321, ranted March 13, 1906, and the second sefactors and also the third selectors may be of this same general type, and the connectors may be of the general type or character shown in Patent No. 815,176, granted March 13, 1906. In any event the arrangement is preferably such that the work or load, as reviously explained, is evenly divided or istributed between a plurality of switching positions, such as automatic switches or operators ositions. If employed in connection with ratus, it will be seen that my invention minimizes the amount of work to be performed by the first selectors, for example that is to say, these first selectors are not compelled to operate to the full limit of their range of adjustment as often or to such an extent'as is true automatic appaof the arrangement employed prior to my invention. In other words, each automatic first-selector switch or even each second-selector switch or third-selector switch, as the case may be, is enabled to perform the work imposed upon it without the necessity of operating to the full range of its switching adjustment, as is true of such switches when the contacts or terminals thereof are multi lied together in the old way. Obviously, t erefore, the wear and tear on the switches is materially reduced, the wear and tear being minimized', so to speak. With respect to the receiving-switchesas, for example, the second selectors, third selectors, or connectors'it will be seen that the arrangement precludes all possibility of the burden of the work being thrown u on some one particular switch, thus distributing the work through-the different switches, regardless of whether the calls are all coming from one particular group of subscribers or more or less evenly from different subscribers throughout the entire exchange. If the calls sent over the trunk-lines are received by operators at ordinary switchboards or operators positions, my improved method of wiring then evenly divides the work of receiving calls among the different switchboard operators and evenly distributes the work among the different trunk-lines; Itis 6V1? dent, therefore, that by my invention I obtain a substantial saving or econom regardless of whether the system is Whol y automatic, partly automatic, or partly manual or wholly manual.

From the foregoing it is evident that my improved method of wiring-that is to say, of multiplying together the contacts and effecting an economical distribution of the work-is ap licabl eto the contacts or terminals of the line-banks and also to the private banks of the diiferent automatic switches.

If a subscriber in the one hundred row of switchboards whose line terminates, say, at

the three thousand one hundred board in thisthe four hundred board of this particular thou- 1 3o &

sand group, andthe secondselector their m-f ceeds automatically to pick out the first idle trunk-line running to the two thousand four hundred board. This gives the calling subscriber aconnector onthe board at whichthe line of the called subscriber terminates. He then calls the last two digits of the number, and thereby causes-the connector to make connection directly with the called subscribers line. Thus with the arrangement shown each switchboard or rack contains the first selectors of all subscribers lines terminating at i f such board or rack, all of the connectors which must be employed for making connection with any of the subsccribers lines thus terminating at this board, and all of the second selectors which must beused by any calling subscriber of this particular hundred row all of t e second selectors to be used by any calling subscriber in the one hundred row of boards in making connection with any subscribers line terminatin at any point in the three thousand row of boards. As shown, the said first selectors are individual to the different subscribers lines and may consequently be termed subscribers individual switches.

I claim as my invention 1. A telephone system comprising a plurality of trunk-lines, a plurality of groups of terminals for said trunk-lines, there being as man terminals in each group as there are trun lines, and all terminals-of each trunkline, being multiplied together from one roup to the other, the members of each row being arranged in series along a definite line, and the terminalsconnected with and allotted to each trunk-line occupying dissimilar positions in the dilierent groups, whereby all terminals occupying similar positions in the different groups are in each case all connected respectively with as many different trunk-lines.

2. A telephone system comprising a plurality of trunk-lines, a plurality of groups of terminals for said trunk-lines, there being as many groups as there are trunk-lines, and also as many terminals in each group as there are trunk-hues, all terminals which are connected similar positions in the different groups,.

with any particular trunk-line occupying diswhereby all terminals occupying similar positions 1n the different groups are in each case connected respectively with as many difi'er ent trunk-lines. a

3. A telephone system comprising a plurality of oups of terminals, trunk-lines connected with said terminals and leading to a lines, there being ss'nsre I connected with and a otted to any particular switching position occupying dissimilar ositions in the different groups, whereby al terminals occupyingsimilar positions in thdifferent groups are in each case connected respectively with as many different switching positions.

rality of trunk-lines leading to a plurality of switching positions,- terminals for the other ends of said trunk-lines, said terminals being arranged in a lurality of groups, and the membersof eac group having a definite arrangement, and eachof said switching os1-' tions bein connected with a plurality o terminals eac arranged in a difierent group, but in each case the terminalsjcon'nected with and alloted to any particular switchinglpos'ition occupying dissimilar positions in .t e different groups, whereby in eachlcase the terminals occupying similar ositions'in the different respectively with as many difierentswitching positions.

5. An automatic telephone system com- .prising a plurality of switching positions,

trunk-lines leading to said switching positions, there being as many trunk-lines as there are switching positions, a plurality of grou s of terminals for the other ends of said trun as many groups as there are trunk-lines, an as many members ineaoh group as there are trunk-lines, in each case the terminals allotted to and connected with any particular trunk-line occupying dissimilar positions in the difierent groups, and in each case the terminals occupying similar positions in the different groups bemgconnectpd respectively with as many different trunkines.

6. An automatic telephone system comprising a plurality of trunk-lines; a plurality of terminals for said trunk-lines, said. terminals being arranged in oups, and each group being divided into su divisions, in each case all terminals connected with a particular trunk-line in the same group occupying similar positions in the difl erent subdivlsions of such group, but. all terminals connected with a particular trunk-lineH-occupying dis similar positions in the different groups, whereby in each case'all terminals occupying like positions in the difierent groups are connected with as many differenttrunk-lines as there are groups. M

I An automatic telephone system comprising a plurality of frames, said frames being arranged in rows'extending at right angles to each other, the rows in 'one direction representing the different thousands, and therows 4. -A telephone system comprising a plucups are allotte 'toand connected in the other direction representing the difierent hundreds, whereby all subscribers whose numbers are under two thousand will be in one row, and all those over two thousand sanere and under three thousand in a row parallel 'therewith, and whereby all subscribers the last three digits of whose numbers are over one hundred will be in a row at right angles to said parallel rows, and whereby all subscribers numbers the last three digits of which are over one hundred and less than two. hundred are in a row parallel to said lastmentioned row, each frame containing the first selectors of this particular group of subscribers, and also containing. the con-,

I than said first selectors, and a plurality of first selectors,

connectors also less in number than said first selectors, said frames being arran ed in rows at ri ht an les to each other, toget er with suitab e cab ing whereby the second selectors of an frame arran ed in a row extendin in one direction may by any 0 the subscribers having first selectors in this row for establishing connection with any of the subscribers having first selectors located in the row containing said second selectors and extending at rightahgles to said first-mentioned row.

9. An automatic telephone system comprising a plurality ofswitch-supports; each support being provided with a plurality of a plurality of second selectors less in number than said first selectors, and a plurality of connectors also less in number than said first selectors, each .su port thus equipped with different kinds 0 switches being a unit in itself and representing a distinct group of subscribers.

10. An automatic telephone system comprising a plnralityof supporting structures,

each structure carrying a plurality of first 7' selectors,-and also a plnrality of connectors, each structure thus equipped with automatic switches be' a unit in itself and as representing a'distinct undred group of subsGribm, each. connector-having a multiple whit is mounted,

t rminal-pf eacliistelephone-line terminating 5s .i; 11.: 'An automatic-* -telephone system comat the structureonw prising a plurality. of switch-frames, a'suit- I able number organisms mounted on -1 each frame, a suitable number of second se- 6Q lectors mounted on each frame and less in -"i' number than tliesaid first selectors theree employed ple cables extending'along the rows in one direction, a normal cable for each switchframe, each normal cable connecting the banks of its connectors with the banks of its first selectors, and second selector multi le cables extendin at right angles to the filist selector mu tiple cables, each frame thus equipped with suitable switches being a unit in itself and representing a distinct group of subscribers.

12. An automatic telephone system comprising a plurality of switches, each switch having a series of terminals, a, plurality of trunk-lines corresponding in number to the number of terminalsin any particular series, and means for connecting each trunk-line with at least one terminal -1n each series, the terminals connected with any particular trunk-line occupying dissimilar positions in the different switches, and in each case the terminals occu ying similar positions in the different switc es being connected with as many diiferent trunk-lines.

13. An automatic telephone system comprising a plurality of switches, a plurality of trunk-lines, each switch containing a series of terminals, means for connecting each trunk-line with at least one terminal in each series, in each case all of the terminals connected with any particular trunk-line occupying dissimilar positions in the different switches, and in each case all of the terminals occupying similar positions in the different switches being connected respectively with as many different trunk-lines, whereby the different switches may all assume first position and thereby each connect with a .difierent trunk-line, or may each assume second ipgsition or third position and so on to'the al position, with the same'result.

14. An automatic telephone system comprising a plurality of switches, a plurality of trunk-lines, each switch having a series of terminals, and .each switch being capable of tions bein such that two or more orany rio number '0 said switches may assume the first, second or third or other position, all at the same time, and thereby-connect with I many diflerent trunk-lines as there are 2 Y switches in operation. I P

15. An automatic telephone systemcom prising a plurality of trimk-lines, a pluralit of switches having terminals connected wit said trunk-lines, each trunk-line being connected with at least one terminal in each chance at a trunk-line other than those with which. the other switches would connect by assuming second position, and so on throughout the range of adjustment of each switch.

v 16.. Anautomatic' telephone system comprising ai.p1urality of 'switchboards, each board being provided with a plurality of subscribe'rs" individual trunk-selecting switchmechanismsor switches, andwith a plurality of connectors, each individual switch adapted to perform a trunking operation in ac-,

cordance with the first digit of the called number, the connectors being less in number than the said individual switches, but each connector having a multiple terminal of each of the different subscribers lines terminating at said individual switches, and each board thus equipped with different kinds-of switch ,ing mac'hineS being a unit in itself and repre- I senting a particular hundred group of" subscribers.

17. An automatic telephone system comprising a plurality of switchboards, each 'board' being rovided with a plurality 01% first selectors an also with a plurality of second selectors, each selector, either first or second,

consisting of an automatic trunk-selecting, switch" mechanism, and each board thus trunk connectionwith all second selectors of the two right-angle rows inwhich its board is included. 7

Signed by me at Qhicago, Cook county,

Illinois, this 6th day of March, 1905.

ALEXANDER a. KEITH.

Witnessesi fl I W. LEE C MPBEUJ, RC. Gniroan.

first direction, and each first selector having 

